It is well known in prior devices to mount a platform as a support surface upon a bearing means so that the platform can rotate in a horizontal plane. The devices are used as exercise devices or playthings by a user standing on the rotationally mounted platform by swinging his or her arms and other body parts so that a swivel motion occurs. These devices have been touted as providing exercise simulating downhill skiing and as a means to provide body conditioning helpful for the downhill skier.
While simulating some of the movements encountered in downhill skiing, all but one of the devices do not provide any simulation of the downhill attitude assumed by skis in use. When one practices with most of the prior art devices and then indulges in alpine or downhill skiing activities, the practice on the prior art device induces muscular and balancing actions which cause the skis to point uphill rather than down the fall line as is desired. It is theorized that the configuration of the prior art device, being horizontal, conditions the user's muscles so that a natural response upon encountering an inclined surface is to cause the skis to be pointed around to the horizontal attitude. While the reason for this response is not fully understood it is noted that in all but one of the prior art devices, locating or shifting body weight to a location eccentric to the axis of rotation of the device does not induce a rotational moment about the axis.
In the one prior art device in which a shifting of body weight to a location eccentric to the axis of the rotation of the device induces a rotational moment about the axis, the members of the device which effectuate the angling of the rotational axis from the perpendicular are not capable of being locked together during use of the device and thus the angular adjustment may slip and change, and the entire device can come apart during vigorous use.
None of the prior art devices contain more than one bearing means to introduce an element of unpredictability to the rotation of the platform.